Dear Harry,
The British Library National Sound Archive (from which I have just
retired) was asked to transfer a collection of about 200 such cylinders. The
NSA cylinder player had to be modified with a new "mandrel" to allow for the
extra length (about two inches more than usual), and because it was an
"amateur" format (in the sense that they weren't meant to be compatible with
Edison commercial cylinders), the speeds varied widely, between 70 and 200
rpm as I recall. Also the groove pitch was tighter, about 150 turns per
inch. The BL cylinder player could cope with both those considerations, but
I know no other reproducer which can. Our cylinders were labelled
"Dictaphone". It seems this format was taken over by another American
company when Edison's cylinder business failed during the slump of 1929.
Peter Copeland